Enclosed Additive Manufacturing System

ABSTRACT

A method of additive manufacture is disclosed. The method may include restricting, by an enclosure, an exchange of gaseous matter between an interior of the enclosure and an exterior of the enclosure. The method may further include running multiple machines within the enclosure. Each of the machines may execute its own process of additive manufacture. While the machines are running, a gas management system may maintain gaseous oxygen within the enclosure at or below a limiting oxygen concentration for the interior.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present disclosure is part of a non-provisional patent applicationclaiming the priority benefit of

U.S. Patent Application No. 62/248,758, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,765, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,770, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,776, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,783, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,791, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,799, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,966, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,968, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,969, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,980, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,989, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,780, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,787, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,795, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,821, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,829, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,833, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,835, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,839, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,841, filed on Oct. 30, 2015,

U.S. Patent Application No. 62/248,847, filed on Oct. 30, 2015, and

U.S. Patent Application No. 62/248,848, filed on Oct. 30, 2015, whichare incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to additive manufacturing and,more particularly, to powder bed fusion additive manufacturing chamberdesigns with high throughput capabilities.

BACKGROUND

Traditional component machining often relies on removal of material bydrilling, cutting, or grinding to form a part. In contrast, additivemanufacturing, also referred to as three-dimensional (3D) printing,typically involves sequential layer-by-layer addition of material tobuild a part. In view of the current state of the art in 3D printing,what is needed are systems and methods for controlling the environmentaround 3D printing machines.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present disclosureare described with reference to the following figures, wherein likereference numerals refer to like parts throughout the various figuresunless otherwise specified.

FIG. 1A illustrates an additive manufacturing system;

FIG. 1B is a top view of a structure being formed on an additivemanufacturing system;

FIG. 2 illustrates an additive manufacturing method;

FIG. 3A is a cartoon illustrating an additive manufacturing systemincluding lasers;

FIG. 3B is a detailed description of the light patterning unit shown inFIG. 3A;

FIG. 3C is one embodiment of an additive manufacturing system with a“switchyard” for directing and repatterning light using multiple imagerelays;

FIG. 3D illustrates a simple mirror image pixel remapping;

FIG. 3E illustrates a series of image transforming image relays forpixel remapping;

FIG. 3F illustrates an patternable electron energy beam additivemanufacturing system;

FIG. 3G illustrates a detailed description of the electron beampatterning unit shown in FIG. 3F;

FIG. 4 is a perspective, partially cut-away, schematic diagram of oneembodiment of a machine for executing a process of additive manufacturein accordance with the present invention;

FIG. 5 is a perspective, partially cut-away, schematic diagram of analternative embodiment of a machine for executing a process of additivemanufacture in accordance with the present invention;

FIG. 6 is a perspective, schematic diagram of one embodiment of anenclosure for controlling a working environment surrounding multiplemachines contained within the enclosure in accordance with the presentinvention;

FIG. 7 is a perspective, schematic diagram of an alternative embodimentof an enclosure for controlling a working environment surroundingmultiple machines contained within the enclosure in accordance with thepresent invention; and

FIG. 8 is a schematic illustration of one embodiment of a self containedbreathing apparatus that may be used by human works operating within(e.g., running, maintaining, and/or monitoring the machines within) theenclosures of FIGS. 6 and 7 in accordance with the present invention.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part thereof, and in which is shown by way ofillustrating specific exemplary embodiments in which the disclosure maybe practiced. These embodiments are described in sufficient detail toenable those skilled in the art to practice the concepts disclosedherein, and it is to be understood that modifications to the variousdisclosed embodiments may be made, and other embodiments may beutilized, without departing from the scope of the present disclosure.The following detailed description is, therefore, not to be taken in alimiting sense.

This disclosure describes a method of additive manufacture that includesrestricting, by an enclosure, an exchange of gaseous matter between aninterior of the enclosure and an exterior of the enclosure. A pluralityof machines supporting various additive manufacturing tasks, as well aspre- or post-processing tasks, can be located within the enclosure. Atleast one machine of the plurality of machines supports an independentprocess of additive manufacture. This independent process can includedirecting a two-dimensional patterned energy beam at a powder bed. Toreduce problems with unwanted chemical reactions, a gas managementsystem maintains gaseous oxygen within the enclosure at or below alimiting oxygen concentration for the interior during task execution.

As seen in FIG. 1, an additive manufacturing system 100 has an energypatterning system 110 with an energy source 112 that can direct one ormore continuous or intermittent energy beam(s) toward beam shapingoptics 114. After shaping, if necessary, the beam is patterned by anenergy patterning unit 116, with generally some energy being directed toa rejected energy handling unit 118. Patterned energy is relayed byimage relay 120 toward an article processing unit 140, typically as atwo-dimensional image 122 focused near a bed 146. The bed 146 (withoptional walls 148) can form a chamber containing material 144 dispensedby material dispenser 142. Patterned energy, directed by the image relay120, can melt, fuse, sinter, amalgamate, change crystal structure,influence stress patterns, or otherwise chemically or physically modifythe dispensed material 144 to form structures with desired properties.

Energy source 112 generates photon (light), electron, ion, or othersuitable energy beams or fluxes capable of being directed, shaped, andpatterned. Multiple energy sources can be used in combination. Theenergy source 112 can include lasers, incandescent light, concentratedsolar, other light sources, electron beams, or ion beams. Possible lasertypes include, but are not limited to: Gas Lasers, Chemical Lasers, DyeLasers, Metal Vapor Lasers, Solid State Lasers (e.g. fiber),Semiconductor (e.g. diode) Lasers, Free electron laser, Gas dynamiclaser, “Nickel-like” Samarium laser, Raman laser, or Nuclear pumpedlaser.

A Gas Laser can include lasers such as a Helium-neon laser, Argon laser,Krypton laser, Xenon ion laser, Nitrogen laser, Carbon dioxide laser,Carbon monoxide laser or Excimer laser.

A Chemical laser can include lasers such as a Hydrogen fluoride laser,Deuterium fluoride laser, COIL (Chemical oxygen-iodine laser), or Agil(All gas-phase iodine laser).

A Metal Vapor Laser can include lasers such as a Helium-cadmium (HeCd)metal-vapor laser, Helium-mercury (HeHg) metal-vapor laser,Helium-selenium (HeSe) metal-vapor laser, Helium-silver (HeAg)metal-vapor laser, Strontium Vapor Laser, Neon-copper (NeCu) metal-vaporlaser, Copper vapor laser, Gold vapor laser, or Manganese (Mn/MnCl₂)vapor laser.

A Solid State Laser can include lasers such as a Ruby laser, Nd:YAGlaser, NdCrYAG laser, Er:YAG laser, Neodymium YLF (Nd:YLF) solid-statelaser, Neodymium doped Yttrium orthovanadate (Nd:YVO₄) laser, Neodymiumdoped yttrium calcium oxoborateNd:YCa₄O(BO₃)³ or simply Nd:YCOB,Neodymium glass (Nd:Glass) laser, Titanium sapphire (Ti:sapphire) laser,Thulium YAG (Tm:YAG) laser, Ytterbium YAG (Yb:YAG) laser, Ytterbium:2O₃(glass or ceramics) laser, Ytterbium doped glass laser (rod, plate/chip,and fiber), Holmium YAG (Ho:YAG) laser, Chromium ZnSe (Cr:ZnSe) laser,Cerium doped lithium strontium (or calcium)aluminum fluoride (Ce:LiSAF,Ce:LiCAF), Promethium 147 doped phosphate glass (147Pm⁺³:Glass)solid-state laser, Chromium doped chrysoberyl (alexandrite) laser,Erbium doped anderbium-ytterbium co-doped glass lasers, Trivalenturanium doped calcium fluoride (U:CaF₂) solid-state laser, Divalentsamarium doped calcium fluoride (Sm:CaF₂) laser, or F-Center laser.

A Semiconductor Laser can include laser medium types such as GaN, InGaN,AlGaInP, AlGaAs, InGaAsP, GaInP, InGaAs, InGaAsO, GaInAsSb, lead salt,Vertical cavity surface emitting laser (VCSEL), Quantum cascade laser,Hybrid silicon laser, or combinations thereof.

For example, in one embodiment a single Nd:YAG q-switched laser can beused in conjunction with multiple semiconductor lasers. In anotherembodiment, an electron beam can be used in conjunction with anultraviolet semiconductor laser array. In still other embodiments, atwo-dimensional array of lasers can be used. In some embodiments withmultiple energy sources, pre-patterning of an energy beam can be done byselectively activating and deactivating energy sources.

Beam shaping unit 114 can include a great variety of imaging optics tocombine, focus, diverge, reflect, refract, homogenize, adjust intensity,adjust frequency, or otherwise shape and direct one or more energy beamsreceived from the energy source 112 toward the energy patterning unit116. In one embodiment, multiple light beams, each having a distinctlight wavelength, can be combined using wavelength selective mirrors(e.g. dichroics) or diffractive elements. In other embodiments, multiplebeams can be homogenized or combined using multifaceted mirrors,microlenses, and refractive or diffractive optical elements.

Energy patterning unit 116 can include static or dynamic energypatterning elements. For example, photon, electron, or ion beams can beblocked by masks with fixed or movable elements. To increase flexibilityand ease of image patterning, pixel addressable masking, imagegeneration, or transmission can be used. In some embodiments, the energypatterning unit includes addressable light valves, alone or inconjunction with other patterning mechanisms to provide patterning. Thelight valves can be transmissive, reflective, or use a combination oftransmissive and reflective elements. Patterns can be dynamicallymodified using electrical or optical addressing. In one embodiment, atransmissive optically addressed light valve acts to rotate polarizationof light passing through the valve, with optically addressed pixelsforming patterns defined by a light projection source. In anotherembodiment, a reflective optically addressed light valve includes awrite beam for modifying polarization of a read beam. In yet anotherembodiment, an electron patterning device receives an address patternfrom an electrical or photon stimulation source and generates apatterned emission of electrons.

Rejected energy handling unit 118 is used to disperse, redirect, orutilize energy not patterned and passed through the energy pattern imagerelay 120. In one embodiment, the rejected energy handling unit 118 caninclude passive or active cooling elements that remove heat from theenergy patterning unit 116. In other embodiments, the rejected energyhandling unit can include a “beam dump” to absorb and convert to heatany beam energy not used in defining the energy pattern. In still otherembodiments, rejected beam energy can be recycled using beam shapingoptics 114. Alternatively, or in addition, rejected beam energy can bedirected to the article processing unit 140 for heating or furtherpatterning. In certain embodiments, rejected beam energy can be directedto additional energy patterning systems or article processing units.

Image relay 120 receives a patterned image (typically two-dimensional)from the energy patterning unit 116 and guides it toward the articleprocessing unit 140. In a manner similar to beam shaping optics 114, theimage relay 120 can include optics to combine, focus, diverge, reflect,refract, adjust intensity, adjust frequency, or otherwise shape anddirect the patterned image.

Article processing unit 140 can include a walled chamber 148 and bed144, and a material dispenser 142 for distributing material. Thematerial dispenser 142 can distribute, remove, mix, provide gradationsor changes in material type or particle size, or adjust layer thicknessof material. The material can include metal, ceramic, glass, polymericpowders, other melt-able material capable of undergoing a thermallyinduced phase change from solid to liquid and back again, orcombinations thereof. The material can further include composites ofmelt-able material and non-melt-able material where either or bothcomponents can be selectively targeted by the imaging relay system tomelt the component that is melt-able, while either leaving along thenon-melt-able material or causing it to undergo avaporizing/destroying/combusting or otherwise destructive process. Incertain embodiments, slurries, sprays, coatings, wires, strips, orsheets of materials can be used. Unwanted material can be removed fordisposable or recycling by use of blowers, vacuum systems, sweeping,vibrating, shaking, tipping, or inversion of the bed 146.

In addition to material handling components, the article processing unit140 can include components for holding and supporting 3D structures,mechanisms for heating or cooling the chamber, auxiliary or supportingoptics, and sensors and control mechanisms for monitoring or adjustingmaterial or environmental conditions. The article processing unit can,in whole or in part, support a vacuum or inert gas atmosphere to reduceunwanted chemical interactions as well as to mitigate the risks of fireor explosion (especially with reactive metals).

Control processor 150 can be connected to control any components ofadditive manufacturing system 100. The control processor 150 can beconnected to variety of sensors, actuators, heating or cooling systems,monitors, and controllers to coordinate operation. A wide range ofsensors, including imagers, light intensity monitors, thermal, pressure,or gas sensors can be used to provide information used in control ormonitoring. The control processor can be a single central controller, oralternatively, can include one or more independent control systems. Thecontroller processor 150 is provided with an interface to allow input ofmanufacturing instructions. Use of a wide range of sensors allowsvarious feedback control mechanisms that improve quality, manufacturingthroughput, and energy efficiency.

FIG. 1B is a cartoon illustrating a bed 146 that supports material 144.Using a series of sequentially applied, two-dimensional patterned energybeam images (squares in dotted outline 124), a structure 149 isadditively manufactured. As will be understood, image patterns havingnon-square boundaries can be used, overlapping or interpenetratingimages can be used, and images can be provided by two or more energypatterning systems. In other embodiments, images can be formed inconjunction with directed electron or ion beams, or with printed orselective spray systems.

FIG. 2 is a flow chart illustrating one embodiment of an additivemanufacturing process supported by the described optical and mechanicalcomponents. In step 202, material is positioned in a bed, chamber, orother suitable support. The material can be a powder capable of beingmelted, fused, sintered, induced to change crystal structure, havestress patterns influenced, or otherwise chemically or physicallymodified to form structures with desired properties.

In step 204, unpatterned energy is emitted by one or more energyemitters, including but not limited to solid state or semiconductorlasers, or electrical power supply flowing electrons down a wire. Instep 206, the unpatterned energy is shaped and modified (e.g. intensitymodulated or focused). In step 208, this unpatterned energy ispatterned, with energy not forming a part of the pattern being handledin step 210 (this can include conversion to waste heat, or recycling aspatterned or unpatterned energy). In step 212, the patterned energy, nowforming a two-dimensional image is relayed toward the material. In step214, the image is applied to the material, building a portion of a 3Dstructure. These steps can be repeated (loop 218) until the image (ordifferent and subsequent image) has been applied to all necessaryregions of a top layer of the material. When application of energy tothe top layer of the material is finished, a new layer can be applied(loop 216) to continue building the 3D structure. These process loopsare continued until the 3D structure is complete, when remaining excessmaterial can be removed or recycled.

FIG. 3A is one embodiment of an additive manufacturing system 300 thatuses multiple semiconductor lasers as part of an energy patterningsystem 310. A control processor 350 can be connected to variety ofsensors, actuators, heating or cooling systems, monitors, andcontrollers to coordinate operation of multiple lasers 312, lightpatterning unit 316, and image relay 320, as well as any other componentof system 300. These connections are generally indicated by a dottedoutline 351 surrounding components of system 300. As will beappreciated, connections can be wired or wireless, continuous orintermittent, and include capability for feedback (for example, thermalheating can be adjusted in response to sensed temperature). The multiplelasers 312 can emit a beam 301 of light at a 1000 nm wavelength that,for example, is 90 mm wide by 20 mm tall. The beam 301 is resized byimaging optics 370 to create beam 303. Beam 303 is 6 mm wide by 6 mmtall, and is incident on light homogenization device 372 which blendslight together to create blended beam 305. Beam 305 is then incident onimaging assembly 374 which reshapes the light into beam 307 and is thenincident on hot cold mirror 376. The mirror 376 allows 1000 nm light topass, but reflects 450 nm light. A light projector 378 capable ofprojecting low power light at 1080p pixel resolution and 450 nm emitsbeam 309, which is then incident on hot cold mirror 376. Beams 307 and309 overlay in beam 311, and both are imaged onto optically addressedlight valve 380 in a 20 mm wide, 20 mm tall image. Images formed fromthe homogenizer 372 and the projector 378 are recreated and overlaid onlight valve 380.

The optically addressed light valve 380 is stimulated by the light(typically ranging from 400-500 nm) and imprints a polarization rotationpattern in transmitted beam 313 which is incident upon polarizer 382.The polarizer 382 splits the two polarization states, transmittingp-polarization into beam 317 and reflecting s-polarization into beam 315which is then sent to a beam dump 318 that handles the rejected energy.As will be understood, in other embodiments the polarization could bereversed, with s-polarization formed into beam 317 and reflectingp-polarization into beam 315. Beam 317 enters the final imaging assembly320 which includes optics 384 that resize the patterned light. This beamreflects off of a movable mirror 386 to beam 319, which terminates in afocused image applied to material bed 344 in an article processing unit340. The depth of field in the image selected to span multiple layers,providing optimum focus in the range of a few layers of error or offset.

The bed 390 can be raised or lowered (vertically indexed) within chamberwalls 388 that contain material 344 dispensed by material dispenser 342.In certain embodiments, the bed 390 can remain fixed, and optics of thefinal imaging assembly 320 can be vertically raised or lowered. Materialdistribution is provided by a sweeper mechanism 392 that can evenlyspread powder held in hopper 394, being able to provide new layers ofmaterial as needed. An image 6 mm wide by 6 mm tall can be sequentiallydirected by the movable mirror 386 at different positions of the bed.

When using a powdered ceramic or metal material in this additivemanufacturing system 300, the powder can be spread in a thin layer,approximately 1-3 particles thick, on top of a base substrate (andsubsequent layers) as the part is built. When the powder is melted,sintered, or fused by a patterned beam 319, it bonds to the underlyinglayer, creating a solid structure. The patterned beam 319 can beoperated in a pulsed fashion at 40 Hz, moving to the subsequent 6 mm×6mm image locations at intervals of 10 ms to 0.5 ms (with 3 to 0.1 msbeing desirable) until the selected patterned areas of powder have beenmelted. The bed 390 then lowers itself by a thickness corresponding toone layer, and the sweeper mechanism 392 spreads a new layer of powderedmaterial. This process is repeated until the 2D layers have built up thedesired 3D structure. In certain embodiments, the article processingunit 340 can have a controlled atmosphere. This allows reactivematerials to be manufactured in an inert gas, or vacuum environmentwithout the risk of oxidation or chemical reaction, or fire or explosion(if reactive metals are used).

FIG. 3B illustrates in more detail operation of the light patterningunit 316 of FIG. 3A. As seen in FIG. 3B, a representative input pattern333 (here seen as the numeral “9”) is defined in an 8×12 pixel array oflight projected as beam 309 toward mirror 376. Each grey pixelrepresents a light filled pixel, while white pixels are unlit. Inpractice, each pixel can have varying levels of light, includinglight-free, partial light intensity, or maximal light intensity.Unpatterned light 331 that forms beam 307 is directed and passes througha hot/cold mirror 376, where it combines with patterned beam 309. Afterreflection by the hot/cold mirror 376, the patterned light beam 311formed from overlay of beams 307 and 309 in beam 311, and both areimaged onto optically addressed light valve 380. The optically addressedlight valve 380, which would rotate the polarization state ofunpatterned light 331, is stimulated by the patterned light beam 309,311 to selectively not rotate the polarization state of polarized light307, 311 in the pattern of the numeral “9” into beam 313. The unrotatedlight representative of pattern 333 in beam 313 is then allowed to passthrough polarizer mirror 382 resulting in beam 317 and pattern 335.Polarized light in a second rotated state is rejected by polarizermirror 382, into beam 315 carrying the negative pixel pattern 337consisting of a light-free numeral “9”.

Other types of light valves can be substituted or used in combinationwith the described light valve. Reflective light valves, or light valvesbase on selective diffraction or refraction can also be used. In certainembodiments, non-optically addressed light valves can be used. These caninclude but are not limited to electrically addressable pixel elements,movable mirror or micro-mirror systems, piezo or micro-actuated opticalsystems, fixed or movable masks, or shields, or any other conventionalsystem able to provide high intensity light patterning. For electronbeam patterning, these valves may selectively emit electrons based on anaddress location, thus imbuing a pattern on the beam of electronsleaving the valve.

FIG. 3C is one embodiment of an additive manufacturing system thatincludes a switchyard system enabling reuse of patterned two-dimensionalenergy. Similar to the embodiment discussed with respect to FIG. 1A, anadditive manufacturing system 220 has an energy patterning system withan energy source 112 that directs one or more continuous or intermittentenergy beam(s) toward beam shaping optics 114. After shaping, the beamis two-dimensionally patterned by an energy patterning unit 230, withgenerally some energy being directed to a rejected energy handling unit222. Patterned energy is relayed by one of multiple image relays 232toward one or more article processing units 234A, 234B, 234C, or 234D,typically as a two-dimensional image focused near a movable or fixedheight bed. The bed (with optional walls) can form a chamber containingmaterial dispensed by material dispenser. Patterned energy, directed bythe image relays 232, can melt, fuse, sinter, amalgamate, change crystalstructure, influence stress patterns, or otherwise chemically orphysically modify the dispensed material to form structures with desiredproperties.

In this embodiment, the rejected energy handling unit has multiplecomponents to permit reuse of rejected patterned energy. Relays 228A,228B, and 22C can respectively transfer energy to an electricitygenerator 224, a heat/cool thermal management system 225, or an energydump 226. Optionally, relay 228C can direct patterned energy into theimage relay 232 for further processing. In other embodiments, patternedenergy can be directed by relay 228C, to relay 228B and 228A forinsertion into the energy beam(s) provided by energy source 112. Reuseof patterned images is also possible using image relay 232. Images canbe redirected, inverted, mirrored, sub-patterned, or otherwisetransformed for distribution to one or more article processing units.234A-D. Advantageously, reuse of the patterned light can improve energyefficiency of the additive manufacturing process, and in some casesimprove energy intensity directed at a bed, or reduce manufacture time.

FIG. 3D is a cartoon 235 illustrating a simple geometricaltransformation of a rejected energy beam for reuse. An input pattern 236is directed into an image relay 237 capable of providing a mirror imagepixel pattern 238. As will be appreciated, more complex pixeltransformations are possible, including geometrical transformations, orpattern remapping of individual pixels and groups of pixels. Instead ofbeing wasted in a beam dump, this remapped pattern can be directed to anarticle processing unit to improve manufacturing throughput or beamintensity.

FIG. 3E is a cartoon 235 illustrating multiple transformations of arejected energy beam for reuse. An input pattern 236 is directed into aseries of image relays 237B-E capable of providing a pixel pattern 238.

FIGS. 3F and 3G illustrates a non-light based energy beam system 240that includes a patterned electron beam 241 capable of producing, forexample, a “P” shaped pixel image. A high voltage electricity powersystem 243 is connected to an optically addressable patterned cathodeunit 245. In response to application of a two-dimensional patternedimage by projector 244, the cathode unit 245 is stimulated to emitelectrons wherever the patterned image is optically addressed. Focusingof the electron beam pattern is provided by an image relay system 247that includes imaging coils 246A and 246B. Final positioning of thepatterned image is provided by a deflection coil 248 that is able tomove the patterned image to a desired position on a bed of additivemanufacturing component 249.

In another embodiment supporting light recycling and reuse, multiplexmultiple beams of light from one or more light sources are provided. Themultiple beams of light may be reshaped and blended to provide a firstbeam of light. A spatial polarization pattern may be applied on thefirst beam of light to provide a second beam of light. Polarizationstates of the second beam of light may be split to reflect a third beamof light, which may be reshaped into a fourth beam of light. The fourthbeam of light may be introduced as one of the multiple beams of light toresult in a fifth beam of light. In effect, this or similar systems canreduce energy costs associated with an additive manufacturing system. Bycollecting, beam combining, homogenizing and re-introducing unwantedlight rejected by a spatial polarization valve or light valve operatingin polarization modification mode, overall transmitted light power canpotentially be unaffected by the pattern applied by a light valve. Thisadvantageously results in an effective re-distribution of the lightpassing through the light valve into the desired pattern, increasing thelight intensity proportional to the amount of area patterned.

Combining beams from multiple lasers into a single beam is one way toincreasing beam intensity. In one embodiment, multiple light beams, eachhaving a distinct light wavelength, can be combined using eitherwavelength selective mirrors or diffractive elements. In certainembodiments, reflective optical elements that are not sensitive towavelength dependent refractive effects can be used to guide amultiwavelength beam.

Patterned light can be directed using movable mirrors, prisms,diffractive optical elements, or solid state optical systems that do notrequire substantial physical movement. In one embodiment, amagnification ratio and an image distance associated with an intensityand a pixel size of an incident light on a location of a top surface ofa powder bed can be determined for an additively manufactured,three-dimensional (3D) print job. One of a plurality of lens assembliescan be configured to provide the incident light having the magnificationratio, with the lens assemblies both a first set of optical lenses and asecond sets of optical lenses, and with the second sets of opticallenses being swappable from the lens assemblies. Rotations of one ormore sets of mirrors mounted on compensating gantries and a final mirrormounted on a build platform gantry can be used to direct the incidentlight from a precursor mirror onto the location of the top surface ofthe powder bed. Translational movements of compensating gantries and thebuild platform gantry are also able to ensure that distance of theincident light from the precursor mirror to the location of the topsurface of the powder bed is substantially equivalent to the imagedistance. In effect, this enables a quick change in the optical beamdelivery size and intensity across locations of a build area fordifferent powdered materials while ensuring high availability of thesystem.

In certain embodiments, a plurality of build chambers, each having abuild platform to hold a powder bed, can be used in conjunction withmultiple optical-mechanical assemblies arranged to receive and directthe one or more incident energy beams into the build chambers. Multiplechambers allow for concurrent printing of one or more print jobs insideone or more build chambers. In other embodiments, a removable chambersidewall can simplify removal of printed objects from build chambers,allowing quick exchanges of powdered materials. The chamber can also beequipped with an adjustable process temperature controls.

In another embodiment, one or more build chambers can have a buildchamber that is maintained at a fixed height, while optics arevertically movable. A distance between final optics of a lens assemblyand a top surface of powder bed a may be managed to be essentiallyconstant by indexing final optics upwards, by a distance equivalent to athickness of a powder layer, while keeping the build platform at a fixedheight. Advantageously, as compared to a vertically moving the buildplatform, large and heavy objects can be more easily manufactured, sinceprecise micron scale movements of the build platform are not needed.Typically, build chambers intended for metal powders with a volume morethan ˜0.1-0.2 cubic meters (i.e., greater than 100-200 liters or heavierthan 500-1,000 kg) will most benefit from keeping the build platform ata fixed height.

In one embodiment, a portion of the layer of the powder bed may beselectively melted or fused to form one or more temporary walls out ofthe fused portion of the layer of the powder bed to contain anotherportion of the layer of the powder bed on the build platform. Inselected embodiments, a fluid passageway can be formed in the one ormore first walls to enable improved thermal management.

Improved powder handling can be another aspect of an improved additivemanufacturing system. A build platform supporting a powder bed can becapable of tilting, inverting, and shaking to separate the powder bedsubstantially from the build platform in a hopper. The powdered materialforming the powder bed may be collected in a hopper for reuse in laterprint jobs. The powder collecting process may be automated, andvacuuming or gas jet systems also used to aid powder dislodgement andremoval

Some embodiments of the disclosed additive manufacturing system can beconfigured to easily handle parts longer than an available chamber. Acontinuous (long) part can be sequentially advanced in a longitudinaldirection from a first zone to a second zone. In the first zone,selected granules of a granular material can be amalgamated. In thesecond zone, unamalgamated granules of the granular material can beremoved. The first portion of the continuous part can be advanced fromthe second zone to a third zone, while a last portion of the continuouspart is formed within the first zone and the first portion is maintainedin the same position in the lateral and transverse directions that thefirst portion occupied within the first zone and the second zone. Ineffect, additive manufacture and clean-up (e.g., separation and/orreclamation of unused or unamalgamated granular material) may beperformed in parallel (i.e., at the same time) at different locations orzones on a part conveyor, with no need to stop for removal of granularmaterial and/or parts.

In another embodiment, additive manufacturing capability can be improvedby use of an enclosure restricting an exchange of gaseous matter betweenan interior of the enclosure and an exterior of the enclosure. Anairlock provides an interface between the interior and the exterior;with the interior having multiple additive manufacturing chambers,including those supporting power bed fusion. A gas management systemmaintains gaseous oxygen within the interior at or below a limitingoxygen concentration, increasing flexibility in types of powder andprocessing that can be used in the system.

In another manufacturing embodiment, capability can be improved byhaving a 3D printer contained within an enclosure, the printer able tocreate a part having a weight greater than or equal to 2,000 kilograms.A gas management system may maintain gaseous oxygen within the enclosureat concentrations below the atmospheric level. In some embodiments, awheeled vehicle may transport the part from inside the enclosure,through an airlock, since the airlock operates to buffer between agaseous environment within the enclosure and a gaseous environmentoutside the enclosure, and to a location exterior to both the enclosureand the airlock.

Other manufacturing embodiments involve collecting powder samples inreal-time in a powder bed fusion additive manufacturing system. Aningester system is used for in-process collection and characterizationsof powder samples. The collection may be performed periodically and theresults of characterizations result in adjustments to the powder bedfusion process. The ingester system can optionally be used for one ormore of audit, process adjustments or actions such as modifying printerparameters or verifying proper use of licensed powder materials.

Yet another improvement to an additive manufacturing process can beprovided by use of a manipulator device such as a crane, lifting gantry,robot arm, or similar that allows for the manipulation of parts thatwould be difficult or impossible for a human to move is described. Themanipulator device can grasp various permanent or temporary additivelymanufactured manipulation points on a part to enable repositioning ormaneuvering of the part.

Referring to FIG. 4, in selected embodiments, a machine 410 may be adevice or system that executes a process of additive manufacture usingcomponents and systems such as previously discussed with at least somelevel of autonomy. For example, a machine 410 may be or comprise anadditive manufacturing system 100, 300. In certain embodiments, theprocess of additive manufacture executed by a machine 410 may comprisepowder bed fusion in the form of direct metal laser sintering (DMLS),electron beam melting (EBM), selective heat sintering (SHS), selectivelaser melting (SLM), selective laser sintering (SLS), or the like. Insome embodiment, an additive manufacturing machine can mechanisms fordirecting a two-dimensional patterned energy beam at a powder bed, suchas described with respect to FIG. 1 as described herein. At amanufacturing facility comprising multiple machines 410, the processesof additive manufacture executed by those multiple machines 410 may beindependent of each other. Thus, different machines 410 may start theirrespective processes at different times, manufacture the same ordifferent parts, and so forth.

In discussing machines 410 in accordance with the present invention, itmay be helpful to define a uniform coordinate system 411. Accordingly,certain machines 410 may correspond to or define longitudinal, lateral,and transverse directions 411 a, 411 b, 411 c orthogonal to one another.The longitudinal direction 411 a may correspond to a long axis of amachine 410. The lateral direction 411 b may combine with thelongitudinal direction 411 a to define a horizontal plane. That is, thelongitudinal and lateral directions may both extend within a horizontalplane. The transverse direction 411 b may extend up and down inalignment with gravity.

Machines 410 in accordance with the present invention may have anysuitable configuration. For example, in selected embodiments, a machine410 may comprise a powder-bed-fusion printer. Accordingly, a machine 410may include an energy patterning system 110, 310, an article processingunit 140, 340 (e.g., a sub-assembly comprising a dispenser 142 forselectively distributing layers of granular material 144, a buildplatform 146 or bed 146 over which various layers of the granularmaterial 144 may be distributed, various walls 148 positioned to containand/or support the various layers of the granular material 144, or thelike or a combination or sub-combination thereof), a controller 150, agantry system 412, or the like or a combination or sub-combinationthereof.

A gantry system 412 may include one or more longitudinal rails 414extending in the longitudinal direction 411 a, a carriage 416selectively moving in the longitudinal direction 411 a along the one ormore longitudinal rails 414, one or more lateral rails (not shown)forming part of the carriage 416, and a print head 418 selectivelymoving in the lateral direction 411 b along the one or more lateralrails. A print head 418 may comprise an energy patterning system 110,310 or some portion thereof. Relative motion in the transverse direction411 c between a print head 418 and a bed 146 (e.g., motion toaccommodate new layers of granular material 144 as they are laid down ona bed 146) may be accomplished by incrementally moving the print head418 away from the bed 146, incrementally moving the bed 146 away fromthe print head 418, or some combination thereof.

A machine 410 in accordance with the present invention may have anysuitable size. For example, the bed 146 of a machine 410 may extend fromabout 0.5 to over 12 meters in the longitudinal and/or lateraldirections 411 a, 411 b. Relative motion between a print head 418 and abed 146 and the sizing of various walls 148 may accommodate a buildup ofgranular material 144 from about 0.5 to over 3 meters.

Referring to FIG. 5, in selected embodiments, a machine 410 inaccordance with the present invention may enable or supportsubstantially continuous additive manufacture of parts that are long(e.g., continuous parts that are longer in the longitudinal direction411 a than the machine 410 can print in its printing range of motion).This may be accomplished by manufacturing a part in segments.

For example, in certain embodiments, a machine 410 in accordance withthe present invention may (1) manufacture a first segment of a part, (2)advance the part a selected distance down a conveyor 420, (3)manufacture a second segment of the part, (4) advance the part aselected distance down the conveyor 420, and (5) repeat until allsegments of the part have been completed. In this manner, additivemanufacture and clean-up (e.g., separation and/or reclamation of unusedor unamalgamated granular material 144) may be performed in parallel(i.e., at the same time) at different locations or zones on the conveyor420. Thus, additive manufacture in accordance with the present inventionneed not stop for removal of granular material 144 and/or parts.

In such embodiments, a bed 146 may form part of, be supported by, and/orride on a conveyor 420. A conveyor 420 may comprise one or more poweredrollers 422 that rotate as directed by a controller 150. Alternatively,a conveyor 420 may comprise a belt extending around a plurality ofrollers 422, one or more of which may be powered and rotate as directedby a controller 150. However, regardless of the configuration of aconveyor 420, an energy patterning system 110, 310 or selectedcomponents thereof may be configured to move incrementally in thetransverse direction 411 c with respect to the conveyor 420. That is, amachine 410 may include a bed 146 that is fixed in the lateral andtransverse directions 411 b, 411 c and a print head 418 that indexes(e.g., incrementally moves) in the transverse direction 411 c to changethe focal point to accommodate new (i.e., higher) layers of material asthey are laid down on the bed 146.

As a granular material 144 is laid down, layer after layer, it may benecessary to contain the granular material 144 so that is does not move,shift, fall away from a part 410, or the like during additivemanufacture. Accordingly, a machine may include one or more walls 148.Certain walls 148 may be stationary. That is, they may not move with aconveyor 420. Other walls 148 may be traveling walls 148 that move witha conveyor 420. For example, in selected embodiments, two stationarywalls 148 may block granular material 144 from falling off the sides ofa conveyor 420 in a lateral direction 411 b, while two or more travelingwalls 148 may contain the granular material 144 in the longitudinaldirection 411 a.

After a completed segment of a part has been advanced down a conveyor420, a new process of additive manufacture may have a “clean slate” tobegin creating the next segment of the part. This new process mayinclude amalgamating selected granules to a near or trailing side of atraveling wall 148, thereby maintaining the longitudinal continuity(i.e., the continuous structural connection in the lateral direction 411a between a segment that is currently being formed and all previouslyformed segments) of the part. Thus, certain traveling walls 148 may formthe boundaries between the various segments of a part. Moreover, suchtraveling walls 148 may intersect any part that spans them. Accordingly,before a part is ready to use, selected portions of such walls 148 mayneed to be removed (e.g., broken off, cut off, ground off, or the like)from the part.

Thus, a machine 410 in accordance with the present invention may defineor include multiple zones. Different tasks may be performed in differentzones. In selected embodiments, different zones may correspond todifferent locations along a conveyor 420. Accordingly, a conveyor 420may advance a part through the various zones of a machine 410.

In certain embodiments, a machine 410 may include three zones. A firstzone may correspond to, include, or span the portion of a conveyor 420where additive manufacture occurs. Thus, a first zone may correspond tothe area on a conveyor 420 where the various layers of granular material144 are being laid down and granular material 144 is being maintained inintimate contact with a part.

A second zone may directly follow a first zone. A second zone may becharacterized by a significant portion of the unamalgamated portion of agranular material 144 moving away from a part. For example, in a secondzone, one or more walls 148 (e.g., stationary walls 148) may terminateso that the unamalgamated portion of a granular material 144 may nolonger be fully contained in the lateral direction 411 b. As a result,some of the unamalgamated portion of a granular material 144 may spilloff the sides of a conveyor 420. The spilling granular material 144 mayfall into one or more containers where it may be collected and reused.

In certain embodiments, some of the unamalgamated portion of a granularmaterial 144 may not “drain” off of a conveyor 420. Accordingly, withina second zone, this remainder of the granular material 144 may beremoved, cleaned-up, or the like in any suitable manner. For example, avacuum mechanism having a collection port that is controlled (e.g.,moved) manually or robotically may be used to collect the remainder.Alternatively, or in addition thereto, one or more flows of pressurizedgas that are controlled (e.g., aimed) manually or robotically may beused to dislodge the remainder from certain crevices, sweep theremainder off a conveyor 420, and/or move the remainder to one or morelocations where it can be accessed by a vacuum.

A third zone may directly follow a second zone. A third zone may becharacterized by a portion of a part within the third zone being exposedto view (e.g., completely, substantially, or partially exposed to viewby the removal or movement of a significant portion of the unamalgamatedportion of a granular material 144) without the part changing itsposition in the lateral and transverse directions 411 b, 411 c.

For example, in certain embodiments, a leading portion of a part mayreach a third zone while a trailing portion of the part is still beingmanufactured within the first zone. Accordingly, in selectedembodiments, a conveyor 420, a bed 146, one or more traveling walls 148,or the like or a combination or sub-combination thereof may cooperate tomaintain a leading portion of a part in the same position in the lateraland transverse directions 411 a, 411 c as the leading portion occupiedwithin the first zone and the second zone. Thus, the position of theleading portion of the part may not excessively disrupt, distort, or thelike additive manufacture that is occurring on a trailing portion of thepart in the first zone.

Accordingly, a machine 410 that enables or supports substantiallycontinuous additive manufacture of parts that are long may itself belong. That is, the conveyor 420 of such a machine 410 may need to belonger than the longest part to the manufactured by the machine 410.

Referring to FIGS. 6 and 7, a manufacturing facility 424 in accordancewith the present invention may comprise one or more machines 410contained within an enclosure 426. Such an enclosure 426 may control oneor more environmental conditions as desired or necessary. For example,an enclosure 426 may protect a printed or to-be-printed material fromunwanted thermal, chemical, photonic, radiative, or electronic reactionsor interactions or the like or combinations or sub-combinations thereof.An enclosure 426 may also protect human operators or other nearbypersonnel from potentially harmful aspects of a machine and machinepowders 410 such as heat, UV light, chemical reactions, radioactivedecay products, and laser exposure.

The one or more machines 410 contained within a particular enclosure 426may all be the same size or of varying sizes. Similarly, the one or moremachines 410 contained within a particular enclosure 426 may all be thesame type or of varying types. For example, in selected embodiments,each of the one or more machines 410 within an enclosure 426 mayamalgamate (e.g., unite, bond, fuse, sinter, melt, or the like) aparticular granular material 144 in a batch process (e.g., in a processexecuted by a machine 410 corresponding to FIG. 4). In otherembodiments, each of the one or more machines 410 within an enclosure426 may amalgamate a particular granular material 144 in a continuousprocess (e.g., in a process executed by a machine 410 corresponding toFIG. 5). In still other embodiments, one or more machines 410 within anenclosure 426 may amalgamate a particular granular material 144 in abatch process, while one or more other machines 410 within the enclosure426 may amalgamate the particular granular material 144 in a continuousprocess.

One or more machines 410 may be arranged in an enclosure 426 so thatsufficient space around the machines 410 is preserved for one or morehuman workers, robots, or the like to access the machines 410, removeparts therefrom, vacuum up unamalgamated granular material 144 forreuse, or the like. Alternatively, or in addition thereto, an enclosure426 may include various gantries, catwalks, or the like that enable oneor more human workers, robots, or the like to access the machines 410(e.g., visually access, physical access) from above. This may be helpfulwhen an enclosure 426 contains one or more large machines 410 whereaccess from the edges or sides thereof may be insufficient for certaintasks.

Certain granular materials 144 may be chemically sensitive to thepresence of oxygen (e.g., gaseous oxygen). For example, certain powdersin an oxygenated environment pose a significant risk of explosion.Alternatively, or in addition thereto, oxygen may act as an oxidizingagent during a high temperature amalgamation of a granular material 144.The resulting oxidation may corrupt, harden, or otherwise adverselyaffect the structural and/or chemical properties of the part beingmanufactured.

Accordingly, in selected embodiments, an enclosure 426 may enable one ormore machines 410 to operate in an environment with oxygen reduced belowatmospheric levels. Such a low-oxygen environment can be formed byrestricting an exchange of gaseous matter between an interior of theenclosure 426 and an exterior of the enclosure 426, while taking stepsto remove or replace oxygen in the enclosure 426. In certainembodiments, this may be accomplished by making an enclosure 426gas-tight or substantially gas-tight and filling the enclosure 426 withan inert or substantially inert gas such as nitrogen, argon,carbon-dioxide, other noble gas, or the like or a combination orsub-combination thereof. In other embodiment, the enclosure pressure canbe lowered. Accordingly, an enclosure 426 may prevent or lower the riskof contamination due to oxidation and/or explosion due to reactivity ofpowdered materials. In selected embodiments, all of the various zones ofa conveyor 420 may be contained within such an enclosure 426 (e.g.,within a single enclosure 426).

In certain embodiments, a low oxygen environment may be an environmentwhere the presence of gaseous oxygen is below a limiting oxygenconcentration (LOC). The LOC may be defined as the limitingconcentration of gaseous oxygen below which combustion is not possibleregardless of the concentration of fuel. The LOC may vary withtemperature, pressure, type of fuel (e.g., type of granular material144), type of inert gas, and concentration of inert gas. The LOCcorresponding to one enclosure 426 may be different than the LOC foranother enclosure 426. Thus, the concentration of gaseous oxygen withinany given enclosure 426 may be maintained below an LOC for thatenclosure 426 (i.e., an LOC that takes into account the temperature,pressure, type of granular material 144, type of inert gas, andconcentration of inert gas, etc. within that enclosure 426).

In other embodiments, a low oxygen environment may be an environmentwhere the presence of gaseous oxygen is well below an LOC. For example,a low oxygen environment may correspond to gaseous oxygen levels atabout 500 parts-per-million by volume or less, about 100parts-per-million by volume or less, about 50 parts-per-million byvolume or less, about 10 parts-per-million by volume or less, or about 1parts-per-million by volume or less. Accordingly, in selectedembodiments, a low oxygen environment in accordance with the presentinvention may be a substantially oxygen-free environment.

In certain embodiments, a manufacturing facility 424 may include one ormore airlocks 428 forming one or more antechambers for a correspondingenclosure 426. An airlock 428 may enable parts, material 144, personnel,or the like to pass into and out of an enclosure 426 withoutcompromising the environment (e.g., the low oxygen and inert gasenvironment) within the enclosure 426. An airlock 428 may include atleast two airtight (or substantially airtight) doors 430 a, 430 b. Afirst door 430 a of an airlock 428 may enable parts, materials 144,personnel, or the like to pass between the interior of the airlock 428and the interior of the corresponding enclosure 426. A second door 430 bmay enable parts, materials 144, personnel, or the like to pass betweenthe interior of the airlock 428 and an exterior environment surroundingthe corresponding enclosure 426. An airlock 428 may also include an gasexchange system (not shown) that may purge and/or vent the airlock 428as desired or necessary to efficiently transition the gaseousenvironment within the airlock 428 between a state compatible with theinterior of the enclosure 426 and a state compatible with theenvironment exterior to the enclosure 426.

In selected embodiments, the ratio of machines 410 within an enclosure426 to airlocks 428 interfacing with the enclosure 426 may be greaterthan one to one (i.e., the number of machines 410 divided by the numberof airlocks 428 may be greater than one). Accordingly, multiple machines410 within an enclosure 426 may share an airlock 428. That is, methodsin accordance with the present invention may include (1) removing froman enclosure 426 through an airlock 428 a first part manufactured by afirst machine 410 in a first process of additive manufacture and (2)removing from the enclosure 426 through the airlock 428 a second partmanufactured by a second machine 410 in a second process of additivemanufacture, wherein the second processing being independent of thefirst process. In certain embodiments, the ratio of machines 410 withinan enclosure 426 to airlocks 428 interfacing with the enclosure 426 maybe two to one or greater (i.e., the number of machines 410 divided bythe number of airlocks 428 may be greater than or equal to two).

In general, the larger the airlock 428, the more expensive it may be tooperate in terms of time, equipment, materials, work, or the like.Accordingly, different airlocks 428 corresponding to a particularenclosure 426 may have different shapes and/or sizes. Thus, passingparts, material 144, personnel, or the like into and out of an enclosure426 may include selected the best airlock 428 for the job.

For example, at least one relatively large airlock 428 corresponding toan enclosure 426 may be large enough (e.g., have a length, width, andheight sufficient) to accommodate the largest part that will bemanufactured by a machine 410 within the enclosure 426, while anotherrelatively small airlock 428 corresponding to the enclosure 426 may bejust large enough to accommodate personnel passing into and out of theenclosure 426. Accordingly, if a human worker needs to enter anenclosure, he or she may do so most efficiently by using the relativelysmall airlock 428.

In selected embodiments, one or more airlocks 428 may be quite smallwith respect to the overall size of a corresponding enclosure 426.Accordingly, those airlocks 428 may be operated without a gas exchangesystem. That is, the release of air into the interior of the enclosure426 and/or the release of insert gas into the environment exterior tothe enclosure 426 corresponding to each cycle of those airlocks 428 maybe sufficiently small as to be negligible or at least within acceptablelimits. Accordingly, those airlocks 428 may provide a quick andefficient mechanism for passing relatively small things into and out ofa relatively large enclosure 426.

In certain embodiments, a manufacturing facility 424 may include one ormore gas management systems 432 controlling the make-up of gaseousmatter within an enclosure 426. A gas management system 432 may maintainconcentrations of inert or substantially inert gas (e.g., nitrogen,argon, carbon-dioxide, or the like or a combination or sub-combinationthereof) above a desired level (e.g., argon at or above about 99.9% byvolume). Alternatively, or in addition thereto, a gas management systemmay maintain concentrations of oxygen and/or water vapor belowatmospheric levels. For example, in one embodiment the desired levelscan be below 0.05% by volume for gaseous oxygen, and below 0.05% byvolume for water vapor.

In certain embodiments, a gas management system 432 may provideclosed-loop recirculation of inert gas within an enclosure 426. However,if small amounts of inert gas escape from an enclosure 426 or areotherwise unrecoverable, a gas management system 432 may add more.Similarly, if small amounts of gaseous oxygen and/or water vaporinfiltrate or are generated within an enclosure 426, a gas managementsystem 432 may remove them. Thus, a gas management system 432 may bematched in capacity to a particular enclosure 426. In general, gasmanagement systems 432 of larger capacity may be applied to enclosures426 of larger size. However, the performance of a gas management system432 may be balanced against the performance of the enclosure 426.

That is, in general, greater performance may be accompanied by greatercost. Accordingly, depending on various factors, it may be more costeffective to pay for greater performance of an enclosure 426 in order tolower the necessary performance of a gas management system 432.Conversely, it may be more cost effective to pay for greater performanceof a gas management system 432 in order to lower the performance of anenclosure 426. Thus, an appropriate and cost-effective balance betweenthe two interrelated systems 426, 432 may be reached.

In selected embodiments, a gas management system 432 may include one ormore intake locations 434 and one or more outlet locations 436. A gasmanagement system 432 may take in gas from within an enclosure 426 atone or more intake locations 434. A gas management system 432 may outputgas into an enclosure 426 at one or more outlet locations 436. Incertain embodiments, one or more outlet locations 436 may be proximateone or more machines 410 (e.g., directly over the print beds 146 of oneor more machines 410) in order to provide a steady flow of inert gasthereto.

In certain embodiments, an enclosure 426 may include one or more windows438. A window 438 may enable one or more persons outside an enclosure426 to see and/or monitor what is happening inside the enclosure 426.Thus, one or more windows 438 may be important safety features of amanufacturing facility 424 in accordance with the present invention.

If desired or necessary, one or more windows 438 may be configured tofilter out certain wavelengths of light that are incident thereon. Forexample, a window 438 may filter out certain wavelengths associated withone or more lasers of one or more machines 410 within an enclosure 426.Alternatively, or in addition thereto, a window 438 may filter outwavelengths associated with outside light that is attempting to enter anenclosure 426 thought the window 438. Thus, a window 438 may protectpersons outside an enclosure 426 and/or photosensitive materials oritems within the enclosure 426.

In certain embodiments, an enclosure 426 may be optically and/orthermally insulated. Optical insulation (e.g., radiation shielding) mayprevent certain wavelengths (e.g., wavelengths corresponding to thelasers of one or more machines 410) may escaping an enclosure. Thermalinsulation may be used to maintain (e.g., more easily maintain) adesired temperature within an interior of the enclosure 426. Forexample, certain processes of additive manufacture may require or runbetter at higher temperatures (e.g., temperatures greater than “roomtemperature” or greater than about 20 to about 25° C.). Such processesmay themselves also generate significant heat. Accordingly, an enclosure426 may be insulated in order to trap at least some of that heat.

An enclosure 426 in accordance with the present invention may be abuilding. Accordingly, in addition to restricting an exchange of gaseousmatter between an interior of the enclosure 426 and an exterior of theenclosure 426, the walls of an enclosure 426 may provide a weatherbarrier. Alternatively, an enclosure 426 may be housed within abuilding. Accordingly, the walls, roof, etc. of the building may providea weather barrier and leave the walls, ceiling, etc. of an enclosure 426to deal exclusively with restricting an exchange of gaseous matterbetween an interior of the enclosure 426 and an exterior of theenclosure 426, reducing a flow of heat between an interior of theenclosure 426 and an exterior of the enclosure 426, or the like. Thismay free an enclosure 426 to be constructed with materials, shapes,methods, or the like that may be incompatible with a weather barrier.

An enclosure 426 in accordance with the present invention may beconstructed in any suitable manner. For example, in selectedembodiments, an enclosure 426 may include one or more walls, ceilings,floors, or the like defining a generally rectangular shape or generallyrectangular sections of an overall shape. The floor may compriseconcrete (e.g., a sealed concrete surface). The walls and/or ceiling maycomprise modular metal sheets or panels that are bolted or otherwisefastened together. One or more sealants, gaskets, or the like may usedbetween adjoining sheets or panels to provide a gas-tight orsubstantially gas-tight seal. Alternatively, or in addition thereto, oneor more films, coatings, or the like may be used to provide a gas-tightor substantially gas-tight seal.

Referring to FIG. 8, the gaseous environment within an enclosure 426 maybe incompatible with the respiratory requirements of one or more humansthat may need to enter and/or work within the enclosure 426.Accordingly, to work within certain enclosures 426 in accordance withthe present invention, one or more workers may don personal protectiveequipment (PPE). Thereafter, when the worker enters an enclosure 426,the PPE may create a barrier between the worker and the workingenvironment within the enclosure 426.

In selected embodiments, the PPE worn by one or more workers may includea self-contained breathing apparatus (SCBA) 440. A SCBA 440 may be aclosed circuit device that filters, supplements, and recirculates orstores exhaled gas (e.g., a rebreather). Alternatively, SCBA may be anopen circuit device that exhausts at least some exhaled gas (e.g.,nitrogen, carbon dioxide, oxygen, water vapor, or a combination orsub-combination thereof) into a surrounding environment. In embodimentswhere an open circuit device is used, the amount exhaled by the one ormore workers within an enclosure 426 may be quite small with respect tothe over size of the enclosure 426. Accordingly, the release of oxygen,water vapor, or the like into the interior of the enclosure 426 may besufficiently small as to be negligible or at least within acceptablelimits (e.g., within the capacity of a gas management system 432 torectify).

In certain embodiments, a SCBA 440 may include a full face mask 442. Ifdesired or necessary, such a mask 442 may be configured to filter outcertain wavelengths of light that are incident thereon. For example, amask 442 may filter out certain wavelengths associated with one or morelasers of one or more machines 410 within an enclosure 426. Thus, a mask442 may protect a worker operating within an enclosure 426 fromincidental laser exposure, which is typically due to reflections, butmay be to a misaligned system or a system undergoing an alignmentprocedure.

In selected embodiments, the PPE worn by one or more workers within anenclosure 426 may protect the workers from potential thermal and/orlaser exposure. For example, when operating in an environment for powderbed fusion, a worker may be exposed to high temperatures. Accordingly,the PPE for that worker may include a protective thermal suit (e.g., asuit that is or is like the structural turnout gear worn byfirefighters), or may contain internal cooling and heat rejection.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims. It is also understood that other embodiments of this inventionmay be practiced in the absence of an element/step not specificallydisclosed herein.

1. A method of additive manufacture, the method comprising: restricting,by an enclosure, an exchange of gaseous matter between an interior ofthe enclosure and an exterior of the enclosure; identifying a pluralityof machines located within the enclosure; executing, by each machine ofthe plurality of machines, an independent process of additivemanufacture comprising directing a patterned energy beam at a powderbed; and maintaining, by a gas management system during the executing,gaseous oxygen within the enclosure below atmospheric level.
 2. Themethod of claim 1, wherein the enclosure comprises an airlockinterfacing between the interior and the exterior.
 3. The method ofclaim 2, further comprising removing from the enclosure through theairlock a first part manufactured by a first machine of the plurality ofmachines in a first process of additive manufacture.
 4. The method ofclaim 3, further comprising removing from the enclosure through theairlock a second part manufactured by a second machine of the pluralityof machines a second process of additive manufacture, the secondprocessing being independent of the first process.
 5. The method ofclaim 4, further comprising assisting, by a human, in removingunamalgamated granular material from around the first part;
 6. Themethod of claim 5, wherein the assisting occurs within the enclosure; 7.The method of claim 6, further comprising wearing, by the human duringthe assisting, a self contained breathing apparatus.
 8. The method ofclaim 7, wherein each independent process of additive manufacturecomprises powder bed fusion.
 9. The method of claim 8, wherein eachindependent process of additive manufacture further comprises directingradiant energy at the selected granules of a granular material.
 10. Themethod of claim 9, wherein each independent process of additivemanufacture further comprises heating, by the radiant energy, theselected granules to at least a melting point thereof.
 11. The method ofclaim 9, wherein each independent process of additive manufacturefurther comprises: distributing a first layer of granules of thegranular material; directing the radiant energy at all granules withinthe first layer that form part of the selected granules; distributing asecond layer of granules of the granular material over the top of thefirst layer; and directing the radiant energy at all granules within thesecond layer that form part of the selected granules.
 12. The method ofclaim 1, further comprising: assisting, by a human within the enclosure,in removing unamalgamated granular material from around a first partmanufactured by a first machine of the plurality of machines in a firstprocess of additive manufacture; and wearing, by the human during theassisting, a self contained breathing apparatus.
 13. The method of claim1, wherein each independent process of additive manufacture comprises:distributing a first layer of a granular material; directing radiantenergy at a first subset of granules within the first layer;distributing a second layer of the granular material over the top of thefirst layer; and directing radiant energy at a second subset of granuleswithin the second layer.
 14. The method of claim 13, wherein eachindependent process of additive manufacture further comprises: meltingor sintering the first subset of granules; and melting or sintering thesecond subset of granules.
 15. The method of claim 14, furthercomprising: assisting, by a human within the enclosure, in removingunamalgamated granules of the granular material from around a first partmanufactured by a first machine of the plurality of machines in a firstprocess of additive manufacture; and wearing, by the human during theassisting, a self contained breathing apparatus.
 16. The method of claim1, wherein the oxygen concentration for the interior space is belowatmospheric levels.
 17. A method of additive manufacture, the methodcomprising: restricting, by an enclosure, an exchange of gaseous matterbetween an interior of the enclosure and an exterior of the enclosure;identifying a plurality of machines located within the enclosure;executing, by each machine of the plurality of machines, an independentprocess of additive manufacture comprising repeatedly (1) distributing alayer of a granular material and (2) amalgamating a subset of granuleswithin the layer by directing radiant energy at the subset of granules;and maintaining, by a gas management system during the executing,gaseous oxygen within the enclosure below atmospheric levels.
 18. Themethod of claim 17, further comprising: assisting, by a human within theenclosure, in removing an unamalgamated portion of the granular materialfrom around a first part manufactured by a first machine of theplurality of machines in a first process of additive manufacture; andwearing, by the human during the assisting, a self contained breathingapparatus.
 19. The method of claim 18, further comprising: removing thefirst part from the enclosure through an airlock; and removing from theenclosure through the airlock a second part manufactured by a secondmachine of the plurality of machines in a second process of additivemanufacture, the second processing being independent of the firstprocess.
 20. An additive manufacturing system comprising: an enclosurerestricting an exchange of gaseous matter between an interior of theenclosure and an exterior of the enclosure; a human accessible airlockproviding an interface between the interior and the exterior for a humanwearing a self contained breathing apparatus; a plurality of machines,each machine thereof executing within the interior an independentprocess of additive manufacture comprising directing a patterned energybeam at a powder bed; and a gas management system maintaining gaseousoxygen within the interior below atmospheric level.